Implants are delivered to a vascular site, such as an aneurysm, of a patient via a microcatheter to occlude or embolize the vascular site. Typically, the implant is engaged at the distal end of either the delivery microcatheter or the guidewire contained within the microcatheter and controllably released therefrom into the vascular site to be treated. The clinician delivering the implant must navigate the microcatheter or guide catheter through the vasculature and, in the case of intracranial aneurysms, navigation of the microcatheter is through tortuous microvasculature. This delivery may be visualized by fluoroscopy or another suitable means. Once the distal tip of the catheter or guidewire is placed in the desired vascular site, the clinician must then begin to articulate the implant in the vascular site to ensure that the implant will be positioned in a manner to sufficiently embolize the site. Once the implant is appropriately positioned, the clinician must then detach the implant from the catheter or guidewire without distorting the positioning of the implant. Detachment may occur through a variety of means, including, electrolytic detachment, chemical detachment, mechanical detachment, hydraulic detachment, and thermal detachment.
Previously, there had been provided 3-dimensional coils which are formed from a straight wire by detachment from the catheter or guidewire. The 3-dimensional coil is typically formed from a metal which upon detachment (e.g., in vivo) reconfigures from the straight wire into a coil shape or confirmation having a secondary structure (i.e., an extended or helically coil confirmation) which under ideal circumstances will comport to the shape of the vascular site to be embolized. However, the in vivo formed coils of the prior art invariably failed to provide shapes which comport to the vascular site and this results in the ineffective embolization of the vascular site. Even when the 3-dimensional coils of the prior art initially comport to the vascular site, the secondary structure of the resulting coils may not be sufficiently stable to retain their comportment with the vascular site. For example, 3-dimensional in vivo formed spherical coils tend to fold upon themselves which leads to secondary structure different from that of the vascular site. Likewise, 3-dimensional in vivo formed cubic coils often collapse on themselves, similar to a “stack of coins” rather than retaining their cubic shape.
In light of the above, there exists a need for a coil implant which substantially conforms to the vascular site to be embolized.